Page 49 - Industrial Ventilation Design Guidebook
P. 49

1 4                                                        CHAPTER 2 TERMINOLOGY



















                  FIGURE 2.3  Definitions of air.



                          • Extract (main, local) air
                          • Recirculated air
                          • Outdoor air
                          • Transferred air (two types—direct or via an air-handling system)
                          • Infiltration
                          • Exfiltration
                          • Indoor air

                      Transferred air can be intentionally or unintentionally transferred. Exhaust air
                      is air leaving the building. Extract air is air leaving the room (it may be partly
                      returned into the room).
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